Control mechanism for an endoscope

ABSTRACT

Control mechanism ( 10 ) for an endoscope including first and second independently rotatable control knobs ( 18,20 ), an inner pinion shaft ( 22 ) fixed to the first control knob ( 18 ), an outer pinion shaft ( 28 ) fixed to the second control knob ( 20 ) and coaxial with the inner shaft ( 22 ) and an intermediate shaft ( 34 ) arranged at least partially inside of the outer shaft ( 28 ) and at least partially around the inner shaft ( 22 ). O-rings ( 42,46 ) between the intermediate shaft ( 34 ) and the inner and outer shafts ( 22,28 ) seal the interior of the endoscope and transfer torque from the inner or outer shaft ( 22,28 ) to the intermediate shaft ( 34 ), which is grounded against rotation and therefore does not transfer torque to the other shaft ( 22,28 ). A non-cross-coupling control mechanism is achieved in which the rotation of one control knob and its associated shaft does not have any effect on the other control knob and associated shaft.

CROSS REFERENCE TO RELATED CASES

Applicant claims the benefit of Provisional Application Ser. No.60/417,835, filed Oct. 11, 2002, and Provisional Application Ser. No.60/485,771, filed Jul. 9, 2003.

The present invention relates generally to control mechanisms formedical instruments designed to inspect internal organs and otherstructure in a body and more particularly to control mechanisms forendoscopes usable for transesophageal echocardiogram (TEE) imaging.

Various medical instruments are designed to be inserted into a humanbody to inspect or image internal organs and other structures in thebody. Endoscopes are one form of such instruments and typically includea handle and a flexible shaft extending from the handle and having adistal or operative end which is inserted into the body through a bodycavity such as the mouth. The distal end of the shaft includes anoptical bundle or CCD array, or another type of image-receiving sensor.

To enable the distal end of the shaft to be capable of controlledadjustable movement, endoscopic flexible links are arranged at thedistal end of the shaft and connect to cables or wires arranged in theshaft and which are mechanically coupled to knobs on the handle. Assuch, the links, and thus the distal end of the shaft, can be moved in acontrolled manner by manual adjustment of the knobs.

Typically, there are two pairs of cables arranged in the shaft, one pairfor flexing the distal end of the shaft in one plane and the other pairfor flexing the distal end of the shaft in a perpendicular plane. Twoindependently rotatable knobs are arranged on the handle and mountedconcentrically one on top of the other to provide for a compact design.An uppermost one of the knobs is coupled to a pair of racks lying in acommon plane via an inner shaft having a pinion engaging with the racksand a lowermost knob is linked to another pair of racks lying in anothercommon plane via an outer shaft having a pinion engaging with thoseracks. The outer shaft is arranged directly around the inner shaft andis coaxial therewith.

Each pinion is situated between the respective associated pair of racks,i.e., the racks are on opposite sides of the pinion so that thedirection of movement of one rack is opposite to the direction ofmovement of the other rack. Rotation of one of the knobs causes rotationof its associated shaft and pinion and thus lateral movement of theracks engaging with the pinion. Since one of the racks is moved in onedirection while the other rack is moved in the opposite direction, onecable is pulled and other pushed thereby causing the distal end of theshaft to turn. Adjustment of the distal end of the shaft in anydirection is thereby enabled by rotating the knobs.

Prior art endoscopes having the above structure are described, forexample, in U.S. Pat. Nos. 4,534,339. 5,479,930 and 5,762,067 describesimilar endoscopes but instead of a rack and pinion movementtransmission mechanism, a pulley and cable transmission mechanism isused.

A problem with the prior art endoscopes of this type is that as one knoband its associated shaft are rotated to cause movement of the coupledpair of racks and cables connected thereto, the torque created by therotation of the shaft is transmitted to the other shaft. Thetransmission of torque from one shaft to the other, and theconsequential rotation of the other shaft, cause undesired movement ofthe other coupled pair of racks and cables connected thereto and thusundesired movement of the distal end of the shaft. The transmission ofrotational force from one shaft to the other is referred to herein as“cross-coupling”.

To overcome this problem, several solutions have been proposed in theprior art. One solution involves minimizing the cross-coupling byproviding a mechanism for increasing friction to the rotational motionof the shafts. The additional friction serves to increase the overallresistance to motion but also detrimentally reduces the operationaltactile feedback available to the operators of the endoscope. Forexample, an O-ring may be arranged between the shafts as in U.S. Pat.No. 5,738,631. The presence of the O-ring between the shafts also servesto seal the interior of the endoscope against the entry of contaminants.However, it has been found that torque is transmitted between the pinionshafts by the O-ring and cross-coupling is thus still a problem.

Another solution to the problem is described in Krauter et al. (U.S.Pat. Nos. 5,464,007 and 5,575,755) wherein an O-ring is placed betweenan inboard end of the outer shaft and a housing frame surrounding therack and pinion units, and another O-ring is arranged between theinboard end of the inner shaft and the housing frame. The placement ofthe O-rings purportedly eliminates torque which might be transmittedbetween the shafts by an O-ring arranged between the pinion shafts (asin U.S. Pat. No. 5,738,631).

Another solution which might prevent the transmission of torque betweenthe shafts in a control mechanism of an endoscope is described in Ouchiet al. (U.S. Pat. No. 4,461,282) wherein a stationary cylinder is fixedto a stationary member of the control mechanism and is interposedbetween the shafts. A cylindrical pipe is arranged around the cylinderand forms part of a brake operating mechanism for engaging a brake toprevent movement of the knobs. When the braking mechanism is activated,rotation of both knobs is prevented. When the braking mechanism is notactivated, torque can be transmitted between the shafts through thestationary cylinder and surrounding pipe. The torque transmissionprevention mechanism is thus integrated in combination with the brakingmechanism leading to an overall complicated structure. Moreover, it is adrawback that to move the inner knob, a large torque is required in viewof the fixing of the stationary cylinder to the stationary member of thecontrol mechanism. That is, since the inner shaft is positioned adjacent(and in apparent contact with) the stationary cylinder, rotation of theinner shaft is difficult because the fixing of the stationary cylindercreates resistance to the rotation of the adjacent inner shaft.

Another drawback in the use of prior art endoscopes occurs whenendoscopes are used for transesophageal echocardiographic (TEE) imaging.For TEE imaging, large angular movement of the distal end of the shaftof the endoscope, up to 120° or more, is often necessary. When theendoscope is constructed to provide increased friction to the rotationalmotion of the shafts in order to obtain large angular movement of thedistal end of the shaft of the endoscope, large manual forces must beexerted on the knobs to overcome the resistance and torque generated bythe rotation of the shafts relative to their mounting structure.

Thus, the prior art does not describe a control mechanism for anendoscope or similar medical instruments which eliminates thetransmission of torque between shafts associated with control knobs andalso enables relatively small rotational force to be applied to theknobs to obtain large angular movement of the distal end of the shaft ofthe endoscope. Similar medical instruments include borescopes and guidetubes and are encompassed herein by the use of the term “endoscope”.

It is an object of the present invention to provide a new and improvedcontrol mechanism for an endoscope.

It is another object of the present invention to provide a new andimproved control mechanism for an endoscope which is particularly usefulfor TEE imaging in which large angular movement of the distal end of theshaft of the endoscope is possible with minimal rotational force on theknobs.

It is yet another object of the present invention to provide a new andimproved control mechanism for an endoscope which eliminates thetransmission of torque between shafts associated with control knobs andalso enables relatively small rotational force to be applied to theknobs to obtain large angular movement of the distal end of the shaft ofthe endoscope.

It is still another object of the present invention to provide a new andimproved control mechanism for an endoscope which also serves to sealthe interior of the endoscope against the entry of contaminants.

In order to achieve these objects and others, a control mechanism for anendoscope in accordance with the invention includes a frame, first andsecond movement transmission devices for causing adjustment of a distalend of a flexible shaft of the endoscope, first and second independentlyrotatable control knobs arranged one above the other on the frame, anouter pinion shaft fixed to the first control knob, an inner pinionshaft fixed to the second control knob and an intermediate shaftarranged between the inner and outer shafts. The inner and outer shaftsare coaxial with one another. The outer shaft engages with the firstmovement transmission device such that upon rotation of the firstcontrol knob, the outer shaft rotates and the first movementtransmission device is actuated. The inner shaft engages with the secondmovement transmission device such that upon rotation of the secondcontrol knob, the inner shaft rotates and the second movementtransmission device is actuated.

The intermediate shaft eliminates the transmission of torque between theshafts so that rotation of one of the shafts does not cause rotation ofthe other shaft. In one embodiment, this objective is achieved by fixingor grounding the intermediate shaft against rotation, possibly by meansof a pin attached to the frame and extending into a slot formed in theintermediate shaft. Sealing of the interior of the endoscope is providedby one or more O-rings arranged between the intermediate shaft and eachof the inner and outer shafts. If placed between the intermediate shaftand the inner shaft, the O-rings may be placed in a respectivecircumferential groove formed in the inner shaft in contact with theinner surface of the intermediate shaft. If placed between theintermediate shaft and the outer shaft, the O-rings may be placed in arespective circumferential groove formed in the intermediate shaft incontact with the inner surface of the outer shaft.

In addition to providing a low-resistance rotary seal between the inneror outer shaft and the intermediate shaft, the O-rings transfer torquefrom the inner or outer shaft to the intermediate shaft, which isgrounded against rotation and therefore does not transfer torque to theother shaft. As such, a non-cross-coupling control mechanism is achievedin which the rotation of one control knob and the shaft associatedtherewith does not have any effect on the other control knob and shaftassociated therewith. Undesired actuation of one movement transmissiondevice when the other is being actuated is thus effectively prevented.

To rotatably mount the inner and outer shafts to the frame, ballbearings may be used. One set of ball bearings is arranged between theframe and the outer shaft for rotatably mounting the outer shaft to theframe. Another set is arranged between the outer shaft and theintermediate shaft for enabling rotation of the outer shaft relative tothe intermediate shaft. Yet another set is arranged between theintermediate shaft and the inner shaft for enabling rotation of theinner shaft relative to the intermediate shaft.

In one embodiment, the intermediate shaft is axially unrestrained sothat it is capable of limited movement in the axial direction (althoughrotational movement is constrained). The intermediate shaft would thusbe capable of moving axially over the O-rings, although such movement isnot intentionally imparted to the intermediate shaft. Movement of theintermediate shaft in the axial direction may be limited by the designand construction of the shafts and other parts of the control mechanism.In one embodiment, at least one hard spacer is arranged between a nutfixed to the frame and ball bearings arranged between the outer shaftand the frame to allow floating of the intermediate shaft.

In another embodiment, the ball bearing mounting the outer shaft on theframe is preloaded and instead of hard spacers, a preload springarranged between the ball bearing and the nut to essentially prevent anyaxial movement of intermediate shaft by creating a large resistance tosuch axial movement.

The invention, together with further objects and advantages hereof, maybest be understood by reference to the following description taken inconjunction with the accompanying drawings, wherein like referencenumerals identify like elements and wherein:

FIG. 1 is a top view of a control mechanism for an endoscope inaccordance with the invention.

FIG. 2 is a cross-sectional view of the control mechanism shown in FIG.1 taken along the line 2-2.

FIG. 3 is an enlarged view of a part of the control mechanism shown inFIG. 1.

FIG. 4 is an enlarged view of part of another embodiment of the controlmechanism in accordance with the invention.

Referring to the accompanying drawings wherein like reference numeralsrefer to the same or similar elements, FIG. 1 shows a control mechanism10 for an endoscope in accordance with the invention including a firstpair of racks 12 arranged in a common plane and a second pair of racks14 arranged in another common plane. The control mechanism 10 isarranged in connection with a control head or control handle of theendoscope, the housing of which is not shown. The control head isconnected to a flexible shaft or gastroscope (not shown) which isinserted into the body cavity for examination of the internal organs orother internal structures.

As known in the art, the racks 12,14 are each coupled to a cable (notshown) that actuates endoscopic flexible links arranged at a distal endof the shaft so that movement of the racks 12,14 causes movement of thecoupled cables and thus movement of the distal end of the shaft of theendoscope. Instead of racks 12,14, other movement transmission devicesfor converting rotational motion into motion of a distal end of theshaft of the endoscope, including those known in the art of endoscopysuch as cable and pulleys, may be used.

The control mechanism 10 includes a housing or frame 16, a first, outercontrol knob 18 and a second, inner control knob 20 arranged below andconcentric with the first control knob 18. The control knobs 18,20 aremounted to be independently rotatable, i.e., rotation of one controlknob does not cause rotation of the other control knob.

The first control knob 18 is connected to a first rotatable pinion shaft22 which includes a shaft portion 24 which extends through an opening inthe second control knob 20 and a pinion portion 26 which engages withthe lowermost pair of racks 14. Rotation of the first control knob 18causes rotation of the first pinion shaft 22 which in turn causesmovement of the racks 14 and thus movement of the distal end of theflexible shaft of the endoscope in one plane, for example, in ahorizontal plane with left or right movement.

The second control knob 20 is connected to a second rotatable pinionshaft 28 which includes a tubular shaft portion 30 which extends aroundand is coaxial with the shaft portion 24 of the first pinion shaft 22and a pinion portion 32 which engages with the uppermost pair of racks12. Rotation of the second control knob 20 causes rotation of the secondpinion shaft 28 which in turn causes movement of the racks 12 and thusmovement of the distal end of the flexible shaft of the endoscope in adirection different from the direction of movement caused by movement ofthe racks 14, usually movement in a plane perpendicular to the directionof movement caused by the movement of the racks 14, for example, in avertical plane with up and down movement.

In view of the positioning of the shaft portion 24 of the first pinionshaft 22 inside the shaft portion 30 of the second pinion shaft 28, thefirst pinion shaft 22 would be considered an inner shaft (and will bereferred to as such below) with the first control knob 18 being an inneror upper control knob whereas the second pinion shaft 28 would be anouter shaft (and will be referred to as such below) with the secondcontrol knob 20 being an outer or lower control knob. This is generallyconventional in the art.

In accordance with the invention, an intermediate shaft 34 is arrangedbetween the inner and outer pinion shafts 22,28 to reduce and ideallyprevent the transmission of torque between the inner and outer pinionshafts 22,28. That is, in the prior art, O-rings are usually used toseal a space between inner and outer, coaxial pinion shafts and are incontact with both the inner and outer shafts so that torque istransmitted upon rotation of one pinion shaft to the other pinion shaftvia the O-rings thereby causing undesired movement of the distal end ofthe endoscope.

The invention eliminates the possibility of transmitting torquegenerated upon rotation of one pinion shaft to another pinion shaft viaO-rings by interposing the rotationally grounded intermediate shaft 34between the inner and outer pinion shafts 22,28 and providing O-rings42,46 between the intermediate shaft 34 and the inner and outer shafts22,28. In view of the presence of the intermediate shaft 34, rotation ofone pinion shaft 22,28 will therefore not result in rotation of theother pinion shaft 22,28 so that undesirable movement of the racks 12,14is prevented.

The intermediate shaft 34 has a tubular portion extending over andcoaxial with the shaft portion 24 of the inner shaft 22 and a detentring 36. The tubular portion extends entirely through and is coaxialwith the shaft portion 30 of the outer pinion shaft 28. The detent ring36 at one axial end of the intermediate shaft 32 is arranged between aflange 38 of the inner pinion shaft 22 and the outer pinion shaft 28 andthe opposite axial end of the intermediate shaft 34 is arranged in arecess 40 of the second control knob 20.

Grounding of the intermediate shaft 34 against rotation may be providedby a pin 58 mounted to the frame 16 (see FIGS. 3 and 4). The pin 58 fitsinto a slot 60 formed in the intermediate shaft 34 and is screwedthrough the frame 16. The slot 60 is oriented to constrain rotationwhile allowing axial movement of the intermediate shaft 34. Instead ofthe pin 58, other mechanisms for grounding or fixing the intermediateshaft 34 against rotation can be used.

The small stretched O-rings 42,46 reduce the magnitude of the torquerequired for the control mechanism 10 while still providing a seal ofthe interior of the endoscope. O-ring 42 is arranged in acircumferential groove 44 formed on the outer surface of the innerpinion shaft 22 and is in contact with an inner surface of theintermediate shaft 34. The O-ring 42 provides a low-resistance rotaryseal between the inner pinion shaft 22 and the intermediate shaft 34.O-ring 46 is arranged in a circumferential groove 48 formed on the outersurface of the intermediate shaft 34 and is in contact with an innersurface of the outer pinion shaft 28 (see FIG. 2). The O-ring 46provides a low-resistance rotary seal between the outer pinion shaft 28and the intermediate shaft 34.

When the second control knob 20 is rotated causing rotation of theassociated outer pinion shaft 28, the rotation of the outer pinion shaft28 relative to the intermediate shaft 34 causes torque to be transmittedto the O-ring 46 and applied via the O-ring 46 to the intermediate shaft34. However, torque is not transmitted to the inner pinion shaft 22 sothat cross-coupling between the manual rotation of the second controlknob 20 and rotation of the first control knob 18 and associated innerpinion shaft 22 is prevented. Similarly, when the first control knob 18is rotated causing rotation of the associated inner pinion shaft 22, therotation of the inner pinion shaft 22 relative to the intermediate shaft34 causes torque to be transmitted to the O-ring 42 and applied via theO-ring 42 to the intermediate shaft 34. However, torque is nottransmitted to the outer pinion shaft 28 so that cross-coupling betweenthe manual rotation of the first control knob 18 and rotation of thesecond control knob 20 and associated outer pinion shaft 28 isprevented.

A “non-cross-coupled” control mechanism, a control mechanism in whichrotation of one shaft and associated control knob does not causerotation of the other shaft and associated control knob through thetransmission of torque between the shafts, is thus achieved. As a resultof the non-cross-coupling provided by the control mechanism inaccordance with the invention, there is no interaction between thecontrol knobs 18,20, i.e., one control knob does not interact with theother, and thus undesired movement of the distal end of the endoscope isprevented.

The presence of the O-rings 42,46 does not create a large resistance torotation of the inner or outer pinion shafts 22,28 so that a relativelylow torque is required to overcome the sealing forces provided by theO-rings 42,46 and turn the control knobs 18,20. In the preferredembodiment, the O-rings 42,46 have a diameter of about 0.05 inches andare stretched over the inner pinion shaft 22 and the intermediate shaft34 to about 60% to 70% of the original diameter. However, larger orsmaller O-rings can be used. Stretching the O-rings 42,46 reduces thepart-to-part molded diameter variations so that variations in theoriginal diameter of the O-rings 42,46 do not adversely affect theconstruction of the control mechanism 10.

The control mechanism 10 further includes low friction, optionallypre-loaded, ball bearings 50 arranged between the frame 16 and the outerpinion shaft 28 for rotatably mounting the outer pinion shaft 28 on theframe 16. Ball bearings 52 are also arranged between the outer pinionshaft 28 and the intermediate shaft 34 for enabling rotation of theouter pinion shaft 28 relative to the intermediate shaft 34. The outerpinion shaft 28 is fixed to the ball bearings 50,52. Additional ballbearings 54 are arranged between the intermediate shaft 34 and the innerpinion shaft 22 for enabling rotation of the inner pinion shaft 22relative to the intermediate shaft 34. Ball bearings 56 are arrangedbetween the inner pinion shaft 22 and the frame 16 for rotatablymounting the inner pinion shaft 22 on the frame 16. The inner pinionshaft 22 is fixed to the ball bearings 54,56. Instead of ball bearings50,52,54,56 other devices which enable relative rotation of coaxialstructures may be used.

In one embodiment shown in FIG. 3, the intermediate shaft 34 is groundedagainst rotation but is not axially constrained so that axial movementof the intermediate shaft 34 is possible, i.e., the intermediate shaft34 can float in the axial direction. The intermediate shaft 34 isshimmed to reduce its floating to virtually zero. In this regard, one ormore hard spacers 64 are provided between the ball bearings 50 and theframe 16 to achieve a minimal endplay, i.e., allow the axial movement ofthe intermediate shaft 34. The spacers 64 preferably have a size toprovide for an allowable endplay of from about 0.001 inches to 0.010inches, although smaller or larger are foreseen. A nut 68 restrains thehard spacers 64.

An additional O-ring 62 may be stretched over the outer pinion shaft 28to provide a seal between the outer pinion shaft 28 and the nut 68 fixedto the frame 16. In the embodiment shown in FIG. 4, instead of afloating intermediate shaft, a preloaded intermediate shaft is provided.In this embodiment, the hard spacers 64 are replaced by a preload spring66, such as a wavy washer spring, which preloads the outer race ofbearing 50 to eliminate any endplay. Thus, while the intermediate shaft34 does not float, it is not axially grounded.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to these preciseembodiments, and that various other changes and modifications may beeffected therein by one of ordinary skill in the art without departingfrom the scope or spirit of the invention. For example, although thecontrol mechanism in accordance with the invention is described for usewith an endoscope, it is contemplated that the control mechanism can beused in other medical and non-medical devices in which movementtransmission devices are controlled by control knobs having coaxialshafts.

1. A control mechanism for an endoscope having a handle, and a flexibleshaft extending from the handle and having a distal or operative endwhich is inserted into a body through a body cavity, the distal end ofthe shaft including an image receiving sensor, the control mechanismcomprising: a frame; first and second movement transmission devices forcausing adjustment of a distal end of the flexible shaft; a firstcontrol knob; a first rotatable pinion shaft rotatably mounted on saidframe and fixed to said first control knob, said first pinion shaftengaging with said first movement transmission device such that uponrotation of said first control knob, said first pinion shaft rotates andsaid first movement transmission device is actuated; a second controlknob rotatable independent of said first control knob; a secondrotatable pinion shaft fixed to said second control knob and coaxialwith said first pinion shaft, said second pinion shaft engaging withsaid second movement transmission device such that upon rotation of saidsecond control knob, said second pinion shaft rotates and said secondmovement transmission device is actuated; an intermediate shaft arrangedat least partially inside of said second pinion shaft and at leastpartially around said first pinion shaft, said intermediate shaft beingarranged to reduce transmission of torque between said first and secondpinion shafts such that rotation of one of said first and second pinionshafts does not cause rotation of the other of said first and secondpinion shafts, said intermediate shaft being axially unrestrained suchthat movement of said intermediate shaft in an axial direction ispossible; first ball bearings arranged between said intermediate shaftand one of said first and second pinion shafts for enabling rotation ofsaid one of said first and second pinion shafts relative to saidintermediate shaft.
 2. The control mechanism of claim 1, furthercomprising at least one O-ring arranged on said first pinion shaft andin contact with said intermediate shaft such that torque transmitted bysaid first pinion shaft to said at least one O-ring is applied to saidintermediate shaft.
 3. The control mechanism of claim 2, wherein saidfirst pinion shaft includes at least one circumferential groove forreceiving a respective one of said at least one O-ring.
 4. The controlmechanism of claim 2, wherein said at least one O-ring is arranged toprovide a rotary seal between said first pinion shaft and saidintermediate shaft.
 5. The control mechanism of claim 1, furthercomprising at least one O-ring arranged on said intermediate shaft andin contact with said second pinion shaft such that torque transmitted bysaid second pinion shaft to said at least one O-ring is applied to saidintermediate shaft.
 6. The control mechanism of claim 5, wherein saidintermediate shaft includes at least one circumferential groove forreceiving a respective one of said at least one O-ring.
 7. The controlmechanism of claim 5, wherein said at least one O-ring is arranged toprovide a rotary seal between said second pinion shaft and saidintermediate shaft.
 8. The control mechanism of claim 1, furthercomprising a first O-ring arranged on said first pinion shaft and incontact with said intermediate shaft such that torque transmitted bysaid first pinion shaft to said at least one O-ring is applied to saidintermediate shaft and a second O-ring arranged on said intermediateshaft and in contact with said second pinion shaft such that torquetransmitted by said second pinion shaft to said at least one O-ring isapplied to said intermediate shaft.
 9. The control mechanism of claim 1,further comprising fixing means for fixing said intermediate shaftagainst rotation.
 10. The control mechanism of claim 9, wherein saidfixing means comprise a pin attached to said frame and extending into aslot formed in said intermediate shaft.
 11. The control mechanism ofclaim 1, further comprising a nut fixed to said frame, additional ballbearings arranged between said second pinion shaft and said frame forrotatably mounting said second pinion shaft to said frame and at leastone hard spacer arranged between said nut and said additional ballbearings to allow floating of said intermediate shaft.
 12. The controlmechanism of claim 1, further comprising a nut fixed to said frame,additional ball bearings arranged between said second pinion shaft andsaid frame for rotatably mounting said second pinion shaft to said frameand a preload spring arranged between said nut and said additional ballbearings, said additional ball bearings being preloaded.
 13. A controland sealing mechanism for an endoscope having a handle, and a flexibleshaft extending from the handle and having a distal or operative endwhich is inserted into a body through a body cavity, the distal end ofthe shaft including an image receiving sensor, the control and sealingmechanism comprising: a frame; first and second movement transmissiondevices for causing adjustment of a distal end of the flexible shaft; afirst control knob; a first rotatable pinion shaft rotatably mounted onsaid frame and fixed to said first control knob, said first pinion shaftengaging with said first movement transmission device such that uponrotation of said first control knob, said first pinion shaft rotates andsaid first movement transmission device is actuated; a second controlknob rotatable independent of said first control knob; a secondrotatable pinion shaft fixed to said second control knob and coaxialwith said first pinion shaft, said second pinion shaft engaging withsaid second movement transmission device such that upon rotation of saidsecond control knob, said second pinion shaft rotates and said secondmovement transmission device is actuated; an intermediate shaft arrangedat least partially inside of said second pinion shaft and at leastpartially around said first pinion shaft, said intermediate shaft beingaxially unrestrained such that movement of said intermediate shaft in anaxial direction is possible; at least one O-ring arranged in contactwith said intermediate shaft and one of said first and second pinionshafts such that torque transmitted by said first or second pinion shaftto said at least one O-ring is applied to said intermediate shaft andtransmission of torque between said first and second pinion shafts isreduced, said at least one O-ring being arranged to provide a rotaryseal between said intermediate shaft and said one of said first andsecond pinion shafts; and first ball bearings arranged between saidintermediate shaft and one of said first and second pinion shafts forenabling rotation of said one of said first and second pinion shaftsrelative to said intermediate shaft.
 14. The mechanism of claim 13,wherein said at least one O-ring is arranged on said intermediate shaftand in contact with said second pinion shaft such that torquetransmitted by said second pinion shaft to said at least one O-ring isapplied to said intermediate shaft.
 15. The mechanism of claim 14,wherein said intermediate shaft includes at least one circumferentialgroove for receiving a respective one of said at least one O-ring. 16.The mechanism of claim 13, wherein said at least one O-ring is arrangedon and in contact with said first pinion shaft such that torquetransmitted by said first pinion shaft to said at least one O-ring isapplied to said intermediate shaft.
 17. The mechanism of claim 16,wherein said first pinion shaft includes at least one circumferentialgroove for receiving a respective one of said at least one O-ring. 18.The mechanism of claim 13, wherein said at least one O-ring comprises afirst O-ring arranged on said intermediate shaft and in contact withsaid second pinion shaft such that torque transmitted by said secondpinion shaft to said at least one O-ring is applied to said intermediateshaft, and a second O-ring arranged on and in contact with said firstpinion shaft such that torque transmitted by said first pinion shaft tosaid at least one O-ring is applied to said intermediate shaft.
 19. Themechanism of claim 13, further comprising a nut fixed to said frame,additional ball bearings arranged between said second pinion shaft andsaid frame for rotatably mounting said second pinion shaft to said frameand at least one hard spacer arranged between said nut and saidadditional ball bearings to allow floating of said intermediate shaft.20. The mechanism of claim 13, further comprising a nut fixed to saidframe, additional ball bearings arranged between said second pinionshaft and said frame for rotatably mounting said second pinion shaft tosaid frame and a preload spring arranged between said nut and saidadditional ball bearings, said additional ball bearings being preloaded.21. The control mechanism of claim 1, further comprising second ballbearings arranged between said intermediate shaft and another one ofsaid first and second pinion shafts for enabling rotation of said otherone of said first and second pinion shafts relative to said intermediateshaft.